Over the last thirty years, participation by girls and women in organized athletics has increased dramatically. This presents unique challenges in the area of sports medicine, orthopaedics, and pediatrics. While the benefits of participation in sports and exercise vastly outweigh the risks of permanent injury, an evolving concern is the number of stress fractures in active women. The female athlete triad (''triad'') describes the coexistence of 3 distinct medical conditions that may occur in athletic girls and women. Originally, the triad included eating disorders, amenorrhea, and osteoporosis. Presently, it includes eating disorders/disordered eating behavior, amenorrhea/ oligomenorrhea, and decreased bone mineral density (osteoporosis and osteopenia). Briefly, when coupled with inadequate nutrition, the high caloric expenditure of exercise training results in a sustained negative caloric balance or low energy availability, which is exquisitely sensed by the hypothalamus, initiating a complex neuroendocrine adaptive cascade. This cascade is associated with changes in the hypothalamic-pituitary-ovarian axis, such that estrogen levels are decreased, resulting in reproductive dysfunction that may include amenorrhea, oligomenorrhea, or anovulation. Low estrogen in otherwise young healthy women, like menopause, is associated with decreased bone mineral density and increased risk of fractures. The triad is not an inevitable consequence of participation in sports or physical activity at any level, however, exercise may contribute to the disruption of caloric balance. The triad is a complex disorder that requires intervention by a multidisciplinary team. Physical therapists bring a unique expertise to the team. The present review summarizes each component of the triad, component linkage, and the role of physical therapy in prevention, assessment, and intervention. J Orthop Sports Phys Ther 2003;33:594-614. Key Words: amenorrhea, eating disorders, osteopenia, women athletes A t the 1996 Summer Olympics, 76 000 fans saw the United States women's soccer team defeat China for the gold medal. This was the largest crowd to ever witness a women's sporting event in this country. Four years later, this attendance record was shattered as the United States hosted the Women's World Cup final. Over the last 12 years, the number of women participating in the Olympic Games has more than doubled, demonstrating a dramatic increase in the number of women competing at the very elite level in sports in the United States and around the world. The increase in elite participation has been paralleled by an increase in opportunities for women participating in all levels of sport and physical activity. We should recognize these important gains and embrace the changes as we celebrate the 30th anniversary of Title IX.The new and increasing opportunities in women's athletics are important because a wide variety of health benefits for girls and women result from participation in sports and exercise. Epidemiology studies 6,30,38 have reported an...